I would start crating him again. If he does not go potty, back in crate. Rinse repeat.

I would put his dog food down for 30 minutes, if he does not eat, pull it up until next meal. No treats, no people food, no bribing. He either eats what you put down, or he goes hungry. Healthy dogs will not starve themselves.

Training, back to basics, do a few quick sessions daily. Correct him for not doing a known command. Do not say a command more than once.

He is feeding off your emotions. You admit that you have been babying him, he does not need you to feel bad for him, he needs you to be a leader. He needs you to be strong, not lay your insecurities and grief on him. Sorry that comes off as harsh, I am sure you are dealing with a lot. Dogs are amazingly resilient. As long as you remain secure and strong, he will follow your lead. You weakness when dealing with him is allowing him to be insecure and test boundaries.